This application is related to copending patent application entitled Steel Rule Die With Scrap Material Ejection filed simultaneously herewith and which is incorporated herein.
This invention relates to steel rule for use in a cutting die and more particularly to rule for a die that facilitates the expulsion of scrap material from the gaps between rule patterns in the die.
Steel rule cutting dies are commonly used for cutting cloth and cloth-like materials such as natural textiles, and synthetic materials such as vinyl. Steel rule dies are particularly advantageous in the repetitive cutting of specific shapes such as clothing, furniture, and automotive interior panels. In brief, a steel rule cutting die typically includes a base substrate or backing board. A length of sharpened blade, known as steel rule, is formed to the shape of the pattern to be cut and is attached to the base substrate with the sharpened cutting edge extending upwardly from the substrate. The die is used in conjunction with a cutting table and a press which may be either single cut or progressive feed. A single cutting die is often constructed with multiple separated rule pieces, to form what is commonly called cutting units or cavities, to enable cutting of multiple patterns with a single pass through the press.
Although the numerous cutting units of the die can sometimes be nested in an efficient manner to reduce scrap, a certain amount of scrap material is inherently produced due to the gaps between adjacent cutting units. Because of the large number of pieces of material cut from a single die, even a small amount of scrap material per piece can add up to a large waste for the manufacturer. Accordingly, reducing the gap between the adjacent cavities could provide substantial savings for the many manufacturers. It is therefore desirable to reduce the gap between adjacent cutting units.
Because of this need to minimize the amount of scrap material, the pieces of rule of adjacent cutting units are frequently placed extremely close together. In regions where two adjacent cutting units are in close proximity to each other, pieces of scrap material may be pinched, wedged, or otherwise trapped between the sections of rule of the adjacent cutting units. This is caused due to the cut scrap material being compressed laterally by the thickness of the outer bevel of the rule on both sides of the gap during the cutting process. The small gaps prevent the scrap material from fully expanding and can sometimes wedge between the rule. Scrap material that becomes stuck in the gaps is difficult and time consuming to remove. Additionally, it has been found that as the scrap material is removed from between adjacent cutting units, smaller pieces of scrap material and lint still remain behind in between the cavities. After numerous cutting operations, the small pieces of scrap material and lint can build up and damage the rule or otherwise inhibit the ability of the die to cut material. Accordingly, adjacent cavities of the die must be separated from one another by a gap sufficiently large to allow for scrap material to be removed after the cutting operation is complete.
In an attempt to eliminate the problem of scrap material becoming lodged in the small gaps, U.S. Pat. No. 5,676,032 to Johnson, the inventor of this application, discloses a steel rule die with closely nested cavities. The specification and drawings of that patent are incorporated herein by reference. This patent discloses the use of offset bevel rule to reduce the gap between the rule of adjacent cutting units, and removed sections of the substrate to permit scrap material to pass therethrough. After the cutting of stack sheets of material, the majority of scrap material can be manually removed from the-die. The small amount of frayed scrap material that would normally remain between the die of adjacent cavities is permitted to fall through the removed sections of the substrate. However, this solution is less than perfect because small pieces of scrap material can still get stuck and wedge between the closely-spaced rule of adjacent cutting units.
It would be desirable to have rule designed for use with a die having closely spaced cavities that does not suffer from the build up of frayed scrap material and enhances the ability to remove the scrap material from between the rule of adjacent cutting units. Preferably, the removal of built up scrap material should not require any additional labor, and it should not increase the time required to perform a cutting process.
According to the present invention, rule for use on adjacent cutting units of a die has a recess or undercut that facilitates the removal of scrap material from between adjacent pieces of rule. The portion of the rule that is undercut is below the cutting edge and on the outside surface of the rule relative to the cutting unit. This helps to a wide passageway for scrap material to fall out through the bottom of the die. As lint and small pieces of frayed material accumulate after each cutting operation, they are forced out of the bottom of the die during the subsequent cutting operation. Therefore, the scrap material never builds up between cutting units to an extent that would inhibit or slow the cutting process or that would cause damage to the die.
The undercut in the steel rule can take a variety of shapes as long as the side surface of the rule that is facing an adjacent cutting unit is spaced farther away from the adjacent cutting unit from the top of the rule to the bottom. The top of the rule, immediately below the sharpened bevel, should be the widest part of the rule. The bottom of the rule, where it attaches to the substrate, should be the narrowest part of the rule. The undercut can take the form of one or more discrete stairstep tapers, or it can take the form of a linear taper in the width of the rule.
It is a further objective of the present invention to provide rule for use in a multi-cavity die with adjacent cutting units in close proximity with each other in which scrap material is easily expelled after a cutting operation.
It is a further objective of the present invention to provide rule for use in a multi-cavity die in which the rule is undercut to allow for expulsion of material after a cutting operation.